A carotenoid pigment is known as one of pigments that are widely used for coloring of food, cosmetics, medicines, and the like. The carotenoid pigment is oil-soluble and characterized in that its color in the state of being dissolved in oil (oleo-resin) is different from that in the form of crystal. Utilizing this characteristic, there are two types of coloring of an aqueous composition using a carotenoid pigment: one type is coloring of an aqueous composition by emulsifying a carotenoid pigment in the form of oleo-resin in it; and another type is coloring of an aqueous composition by dispersing pulverized crystals of a carotenoid pigment in it.
Among the above two types of the aqueous compositions, the carotenoid pigment crystal dispersion type is inferior in stability to the oleo-resin emulsion type. It was found that aggregation of crystal particles of the former type is accelerated, particularly, in a condition of low temperature such as 10.degree. C. or lower. This characteristic leads deterioration of the visual commercial value as a result of precipitation of aggregates of the crystals when used in drinks or the like, which have many opportunities of distribution, preservation, and exhibition at a low temperature. Therefore, when a carotenoid pigment is applied to food, the use of the carotenoid pigment crystals for coloring by dispersing in an aqueous composition is limited to solid foods such as kneaded products, jellies, candies, ice candies, and the like, which are obtained by dispersing the pigment in a composition and solidifying it. Thus, it is difficult to apply them to drinks (liquid food).
Known conventional methods of improving dispersion stability of a carotenoid pigment in an aqueous composition include a method of adding viscous polysaccharide such as pectin, or xanthane gum together with a carotenoid pigment, a method of using a water-dispersible carotenoid pigment powdery composition comprising a carotenoid pigment having a particle diameter of less than 0.1 .mu.m and sodium laurylsulfate (Japanese Patent Application Laid-open No. 52-84232), a method of dispersing a pulverized carotenoid pigment in an aqueous composition (Japanese Patent Application Laid-open No. 7-90188), a method of incorporating a carotenoid pigment, particularly .beta.-carotene, in cyclodextrin and dispersing it in an aqueous composition (Japanese Patent Application Laid-open No. 62-267261), a method of incorporating lycopene, one of carotenoid pigments, in .gamma.-cyclodextrin, and adding the resulting inclusion compound in an aqueous composition together with gluten and/or ascorbic acid (Japanese Patent Application Laid-open No. 8-259829), and the like. It cannot be said that dispersion stability of a carotenoid pigment in an aqueous solution prepared by any of the above methods is not satisfactory in a low temperature range.